(1) Field of the Invention
The invention applies to turbomachines, and in particular to aviation turbines and to industrial gas turbines. More particularly, the invention relates to the turbines of such turbomachines, and more precisely still, it relates to adjusting the resonant frequency of the blade inserts of such turbines.
(2) Description of Related Art
Usually, the blade inserts of a turbine comprise a single blade connected both to an outer platform and to an inner platform, which inner platform is in turn extended by a root for fixing the insert to the turbine rotor.
It is important to ensure that undesirable vibrations do not appear in the turbines of turbomachines, and in particular vibrations caused by resonance phenomena, at different operating speeds of the turbomachine.
Unfortunately, given constraints in terms of complying with the required aerodynamic profile for blades and complying with weight and size constraints, the options available for adjusting the resonant frequency of a blade insert by acting on its shape are limited.
Thus, French patent document FR 1 578 562 proposes giving the single-blade inserts of a wheel different characteristics such as roots of different lengths in the radial direction or different dimensions at the levels where the inserts are attached to the rotor. Nevertheless, such solutions are penalizing in terms of insert weight and in terms of complexity in building the rotor or in attaching inserts to the rotor.